001 Teacher The Cell

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TEACHER COPY

Living things are made of cells.

We will now study cells in detail.

CELL STRUCTURE AND FUNCTION-

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Cell membrane- with proteins “floating” in it.

CELL MEMBRANE

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Membranes of the cell are selectively permeable (sometimes called semi-permeable)

1-Selective Permeability

– They allow some substances to cross more easily than others

– They block passage of some substances altogether

– Without this selectivity, the cell could not survive

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Cytoplasm

Cytoplasm is the liquid in the cell and all the organelles in a cell.

The liquid part by itself is called cytosol.

The organelles are the little “organs” (not really organs- but we can think of them that way) that are in the cell.

Most have membranes very similar to the cell membrane

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Cell model with cytoplasm (cytosol & organelles)

Think of the cytoplasm as everything inside the cell.

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Organelles

Organelles are organized like small cells

Complete with their own phospholipid-bilayer membrane.

This membrane performs many of the same functions (basically controlling what goes in and out) as in the cell membrane

The organelles are in the cytoplasm

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VesiclesAre packages of various molecules that need to be moved from one place to another in a cell.

Below- a vesicle “budding” or “pinching off ” from an organelle.

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The vesicle fuses with the cell membrane.

This is part of the process of exocytosis- when the contents of a vesicle are released from the cell to be used elsewhere.

And releases its contents

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The vesicle membrane is now part of the cell membrane.

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Think pair share

1. What are the two functions of the cell membrane?

a. It is the outer boundary of the cell.

b. It controls which molecules go from one side of the membrane to the other

2. What is selective permeability?

Membrane controls what molecules pass through it.

3. Name the two parts of the cytoplasm.

a-liquid or cytosol

b-organelles

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Think pair share

1. What quality does the cell share with every organelle?

A lipid bilayer. In other words, a double layered fat membrane.

2. Describe a vesicle in detail- structure, and function.

A membrane bound container with macromolecules, that can be moved around the cell. Vesicles can form from the cell membrane during endocytosis, or from organelles.

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Cell Nucleus

Cell nucleus showing the nuclear envelope, nucleolus and chromatin. Chromatin is DNA that is visible, like fine threads.

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The nucleus is the storehouse of information and the manager of the cell

Cell Nucleus

– Genes in the nucleus store information necessary to produce proteins

– The information must be copied from the DNA and then taken out of the nucleus so proteins can be made elsewhere in the cell.

– More about building proteins, and where that happens, later.

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Ribosomes

Chromatin (uncoiled

chromosomes)Nuclearenvelope Nucleolus Pore

Diagram of nucleus and associated organelles.

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The nucleus is bordered by a membrane called the nuclear envelope

Structure and Function of the Nucleus

– The nucleus contains chromatin (uncoiled chromosomes)

– Chromatin = DNA wrapped around proteins– The nucleus contains a nucleolus (containing

RNA)– We will explain the nucleolus and RNA a little

later in this section.– Right now, understand how DNA looks.

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Think pair share

1. What is the main function of the nucleus?

Storage of DNA. Another way to say it is that the nucleus controls the whole cell.

2. Can DNA leave the nucleus?

NO!

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DNA

DNA- deoxyribonucleic acid.

Contains the “directions” to allow any cell in your body to do everything it needs to do.

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This is one “model” of DNA. It is supposed to show that it is like a ladder, with rungs, that is twisted. This model is focused on showing some other details that we will learn about later, so it does not show the twisting very well. You will see this model many times, later in this course.

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DNA molecules are built just like a ladder. To make a better model, like the one in the next slide, we just need to twist the ladder into a spiral.

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Here is a much better model for understanding that DNA is built just like a ladder that has been twisted.

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DNA

Chromosomes & chromatin.Chromosomes are basically just DNA

wrapped up very tightly, almost exactly as you would coil an incredibly long rope if you wanted to fit the most rope in the smallest area.

Chromatin is that exact same DNA, in an uncoiled, kind of messy pile on the table.

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This is a close up electron micrograph of bacterial DNA in its uncoiled state called chromatin.

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Chromatin

What’s this????

24Model of DNA

1 This…

2 …..is drawn as this…

3 …wrapped around these proteins called histones.

A real picture

25Model of DNA

Histone, a protein

1-This DNA, wrapped around histones……..

2-..is coiled, and coiled again, many times……

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Coil these, and coil them some more, until the result is…………….

This…….

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3

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You started with chromatin, and coiled it into a chromosome

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3

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You can actually see the little beads in the far right electron micrograph. They are histones.

histones

29Chromosomes

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Chromatin vs Chromosome

The DNA in cells is usually in the form of chromatin.

Chromosomes are formed when cells begin to divide.

So the picture on the preceding page, of a chromosome, is NOT what you should think of when DNA is doing its “normal” job of directing the cell to do all it needs to do.

Chromatin- ready for “normal” work

ready for cell to divideChromosome-

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Cell dividing- showing chromosomes very clearly.

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Think pair share

1. Explain chromatin and chromosomes.Chromatin is DNA wrapped around proteins, but

not tightly coiled. Unravelled, for everyday functions, easy to access and read.

Chromosomes are chromatin tightly wrapped, coiled compactly, getting ready for cell division.

2. What is a histone? The proteins around which DNA is ravelled. ACTIVITY- INSTRUCTOR LEAD CLASS IN

BUILDING A CHROMOSOME FROM ROPE AND PLASTIC GOLF BALLS.

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DNA never leaves the nucleus.

DNA is “double stranded.

Single copies of it, called RNA, leave thru nuclear pores, and direct protein formation

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Chromatin vs chromosome

All this coiling must have a reason.

Think of trying to copy DNA. How is it done?

The RNA has to be able to access or “get to” the DNA in order to actually copy one of its strands.

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The RNA at right is a single stranded copy of the DNA.

Electron micrograph of Chromatin

Model of chromatin

Real chromosome

Model of part of a chromosome

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So, which one will it be possible to “read”?

This chromatin or

This chromosome?

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An actual electron micrograph of a nuclear membrane, showing pores.

Nuclear membraneNuclear

pores

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Close up of electron micrograph looking at a cross section of the nucleus.

NM= nuclear membrane.

P= nuclear pore.

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Another electron micrograph of a nucleus, showing a nuclear pore

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A pretty cool close up of a freeze etched nucleus, using an electron micrograph. You can see the nuclear pores.

Nuclear pores

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Nuclear pores

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Here is a model of RNA.

Ribonucleic Acid.

It is single stranded, as you can see.

It is very similar to DNA, and has most of the same molecular structure.

RNA is a single stranded copy of the information in DNA and oversees protein production

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NucleolusThe nucleolus is a specialized area of DNA that has information needed to make ribosomes.

Shows up as a dark spot inside the nucleus when we view a cell on a slide.

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DNA controls the cell by transferring its coded information into RNA

How DNA Controls the Cell

– The information in the RNA is used to make proteins at the ribosomes

– After the protein is produced, the mRNA is recycled back to the nucleus

DNA

RNA

Nucleus

CytoplasmRNA

Ribosome reads RNA

Protein

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Think pair share

1. Take me from being DNA to a finished protein.

DNA- copied into mRNA. mRNA leaves the nucleus thru a nuclear pore. mRNA meets up with a ribosome, and the ribosome “reads” the mRNA for the recipe to make a protein. You should know by now that a protein is a string of amino acids that folds into a shape.

2. What is the function of the nucleolus?

It has information to make ribosomes.

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Movie clip #1- Play the movie- “7.2 Eukaryotic Cells- DNA thru Translation” by double clicking on the blue square. 10 min.

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Endoplasmic Reticulum & Ribosomes

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The Endoplasmic Reticulum

endoplasmic reticulum (ER)

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The endoplasmic reticulum (ER)shown by itself- a diagram


Figure 4.11

Nuclearenvelope

Ribosomes

Rough ERSmooth ER

A cross section of the ER, shown in an electron micrograph.

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Present in Eukaryotic Cells, not in prokaryotic cells.

That means modern cells vs. bacteria.

No Endoplasmic Reticulum in this bacteria, a prokaryotic cell.

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ER- Features & Functions

provides an extensive surface area for a broad array of chemical reactions.

Manufacturing site of proteins and lipids (fats).

– Some used within the cell- released from ER to cytoplasm.

– Some exported from cell.• Enclosed in vesicles and transported to

Golgi Apparatus, a second processing center for the cell which we will study in the near future.

• Golgi apparatus sends it out of cell in vesicle

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ER- Features & Functions

provides an extensive surface area for a broad array of chemical reactions.

Electron micrograph

Notice in the diagram how much surface area the ER has. Think of the surface area as a large workbench- lots of room to put chemicals together.

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Why all this surface area?

Your cells perform thousands of chemical reactions every single day.

Enzymes are proteins that initiate and oversee chemical reactions.

They need working space on which to perform these chemical reactions. Just like putting together parts in a factory.

The ER provides surfaces for this to happen.

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Nucleus

ER

vesicle Golgi apparatus

vesicle

Exported product

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Two Kinds of Endoplasmic Reticulum- Rough & Smooth

ROUGH Endoplasmic Reticulum (rough ER)

– In most cells, a portion of the ER membrane is lined on its outer surface with ribosomes.

– These are the small protein-synthesizing organelles built in part by the nucleolus.

– In this case, the ER is spoken of as "rough" because it actually looks rough when viewed under a microscope.

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Nuclearenvelope

Ribosomes

Rough ER

Smooth

ER

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A close up of the rough ER. The dark spots indicated by arrows are ribosomes that are on the surface of the membrane of the ER.

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Two Kinds of Endoplasmic Reticulum- Rough & Smooth

•SMOOTH Endoplasmic Reticulum (smooth ER)

•Where no ribosomes line its membrane, the ER is described as "smooth".

•Both kinds of ER usually exist at the same time in a cell.•Smooth ER manufactures lipids.

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Rough ER Is A Major Site Of Protein Synthesis

RNA is a single stranded copy of DNA (which is double stranded). RNA copies the information from DNA, in the nucleus.

RNA oversees protein production (it has the recipe)

RNA moves through nuclear pores, into the cytosol, and eventually to the Endoplasmic Reticulum, where it joins with a ribosome.

It is here, on the surface of rough ER, that most proteins are made.

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DNA never leaves the nucleus.

DNA is “double stranded.

Single copies of it, called RNA, leave thru nuclear pores, join with ribosomes on the surface of the rough ER, and produce proteins.DNA

RNA w/ info to make proteins

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Here is a model of RNA.

Ribonucleic Acid.

It is single stranded, as you can see.

It is very similar to DNA, and has most of the same molecular structure.

RNA is a single stranded copy of the information in DNA and oversees protein production

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DNA molecules are built just like a ladder. To make a better model, like the one in the next slide, we just need to twist the ladder into a spiral.

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Here is a much better model for understanding that DNA is built just like a ladder that has been twisted.

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Model of ER, nucleus, nuclear pores, ribosomes and RNA.

The RNA is leaving the nucleus through nuclear pores and traveling to the outer surface of the ER, where it joins with a ribosome.

DNA & RNA in nucleus

RNA travels thru nuclear pore

RNA joins ribosome on outer surface of ER.

Inner surface of ER

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Freeze etched electron micrograph showing nuclear pores.

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Once the ribosome binds to the ER, along with RNA (with the “ingredients list”)

the translation (that means translating from RNA language to an actual protein) begins

and the protein being synthesized on the ribosome is threaded through channels into the ER.

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Ribosome joined with RNA (RNA not shown)

Amino acid chain (a protein) going inside ER.

Often packaged in vesicle for transport.

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•Ribosomes may also be located elsewhere in the cytosol.

•They float somewhat freely throughout the cell and are called free ribosomes.

• Proteins synthesized on free ribosomes in the cytoplasm are not destined for

•export from the cell •or for incorporation into membranes (remember cell membranes have proteins mixed in with the lipid bilayer).

•They are released to function as enzymes within the cell.

ribosome RNA

Amino acid chain (protein)

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Smooth ER

The smooth ER has no ribosomes and it is here that lipids are produced.

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RIBOSOMES

Ribosomes are the protein builders of the cell.

When they build proteins, scientists say that they synthesize the proteins.

Ribosomes are found either floating around in the cytoplasm or attached to the Endoplasmic Reticulum (ER).

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Think pair share

1. Explain the major functions of ER.

a- surface area for chemical rxns.

b- the manufacturing site of proteins and lipids

2. Name the two kinds of ER and the fxn of each.

b- Rough ER

Protein production site.

b- Smooth ER

Lipid production site.

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Think pair share

1. Track mRNA from the nucleus to a protein leaving the cell.

Delete this from student copy- look at next slide for the answer.

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Nucleus

ER

vesicle Golgi apparatus

vesicle

Exported product

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Think pair share

1. Explain how a finished amino acid chain gets from the surface of the rough ER into a vesicle that is bound for the Golgi Apparatus.

Delete from student copy- see next slide.

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Ribosome joined with RNA (RNA not shown)

Amino acid chain (a protein) going inside ER.

Often packaged in vesicle for transport.

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RIBOSOMES

The free floating ribosomes – synthesize proteins that will be used

inside the cell.

The ribosomes attached to the ER synthesize proteins that may be used

– inside the cell, or – may be sent outside the cell.

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•Recall that RNA is a copy of DNA, and DNA is in the nucleus.

•RNA leaves the nucleus through nuclear pores, and makes its way to a ribosome………

•on the surface of the endoplasmic reticulum •or joins with a free ribosome.

•The RNA has the “ingredients” list for the protein to be made. •The ribosome has the enzymes to initiate and control the chemical reactions needed to put the protein together and is a sort of a machine that causes protein synthesis to occur.

RIBOSOMES

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A schematic diagram showing RNA moving from the nucleus to the cytoplasm and joining with a ribosome to manufacture a protein.

WHAT’S THIS????

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A single ribosome, shown in sequence, as it moves along a molecule of RNA and reads the sequence of amino acids to make a polypeptide chain.

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Think pair share

1. What is translation?

Translating mRNA language for the recipe for a protein into an actual protein.

2. [Review question] Explain the relationship of a polar hydrogen on an amino acid, to a folded protein.

Hydrogens on various amino acids are polar. The order of amino acids determines exact locations of hydrogen bonds. This determines the exact folding, and thus particular shape, of a given protein.

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Think pair share

1. In a nutshell, explain how DNA controls the entire cell, and in fact, your entire body.

DNA codes for proteins, which means all structures, enzymes and hormones. It has the code for everything your body does.

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Golgi Apparatus & Lysosomes

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Golgi was an Italian scientist who discovered this organelle.

An apparatus is an old fashioned word for a complex machine.

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Golgi apparatus

receives vesicles from the endoplasmic reticulum containing proteins.

Modifies molecules and transports them in transport vesicles.

creates a special kind of digestive vesicle called a lysosome which is discussed in more detail below.

can absorb molecules that are put into the cytosol by digestive acivities of lysosomes.

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Another model of the Golgi apparatus.

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The Golgi apparatus – gathers, – stores, – modifies (for example, removal

of water or emulsification of lipids),

– and packages……..

secretory products for distribution in membrane-wrapped secretory vesicles

•When we say a cell secretes a product, we mean that it creates it, using its organelles and chemicals that it has gathered.

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Electron micrograph of a Golgi Apparatus

Transport vesicles

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Model of Golgi Apparatus in a possible location within the cell.

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Substances packaged in vesicles can be sent to different cellular compartments or exported from the cell.

Vesicles from ER, coming in…..

Vesicles going out- to cell membrane or other organelles



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Lysosomes

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Lysosomes

Lysosomes- these special vesicles with very powerful digestive enzymes, are created by the Golgi apparatus.

Cell digestion is done by lysosomes.

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Lysosomes

Lysosomes- these special vesicles with very powerful digestive enzymes, are created by the Golgi apparatus.

Cell digestion is done by lysosomes.

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A lysosome is a membrane-enclosed sac which contains very powerful digestive enzymes.

It is really just a special kind of vesicle.

Together, all the lysosomes in a cell make up its digestive system.

Lysosomes break down macromolecules, damaged organelles, or even other cells, like bacteria, which a cell has “eaten”.

The cell uses the digested products to make all of its own new products- macromolecules, membranes, organelles and so on. Lysosomes are created by the Golgi apparatus.

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•Many cells can “capture” molecules or other “cell food” from outside the cell

•This is called endocytosis.

•Endocytosis is pinching the cell membrane inward, pulling the “food” within the cell and forming a vesicle around it.

•The “food” within vesicle must be digested.

•The lysosome fuses with the food vesicle, and the enzymes can now digest whatever is in the secondary lysosome (food vesicle joined w/lysosome).

“Eating stuff from outside the cell.

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•A kind of endocytosis- called phagocytosis.

•Phago- “eating”

•Cyto- cell

•“Cell eating”

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Diagram of cell performing endocytosis.

This could be a white blood cell, which can move, surround and “eat” bacteria.

Bacterium

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Plasmamembrane

Digestive enzymes

Food vesicle is formed.

Digestion2○ lysosome

Lysosome

Cell pinches in here

. Once the “food” is within vesicle, it must be digested by lysosomes.The lysosome fuses with the food vesicle and digests the contents. Useful products from this digestion pass into the cytosol, to be re-absorbed by various organelles

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Lysosome breaking down damaged organelle

Lysosome

Damagedorganelle

Digestion

Lysosomes digest damaged organelles as well.

The lysosome simply surrounds the damaged organelle (or a piece of one) and digests it.

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Enzymes are protein molecules that either speed up or allow chemical reactions.

Lysosomes contain powerful

digestive enzymes.

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Because they are proteins, we know enzymes start out in the rough ER and are sent to the Golgi apparatus.

Rough ER

Golgi apparatus

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The Golgi apparatus packages these enzymes into a vesicle, and a lysosome has been created.

Lysosome- really just a specialized vesicle.

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Waste products from digestion by lysosomes are disposed of when the secondary lysosome travels back to the cell membrane and accomplishes exocytosis.

Food vesicle, digestion complete.

exocytosis

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•Exocytosis- contents of the vesicle leave the cell.

•Could be digested material from a vesicle.

•Or products for export to be used elsewhere in the body.

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Movie clip #2- Endocytosis and exocytosis.

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If the very powerful digestive enzymes in lysosomes were left to float around the cell, they would actually digest the cell itself. They MUST be contained. This brings up an important and unanswered question: If the enzymes in a lysosome can break down anything in a cell, why don't they break down the lysosome too?

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Rough ER

Contains digestive enzymes

Repackages digestive enzymes into a lysosome

Food captured

Food captured

digestion

Cell gets rid of unusable digested material by exocytosis

Joining of food vesicle and lysosome

Food vesicle

Food vesicle

This slide will be on the test!!!!

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Think pair share

1. What are the two main functions of the Golgi, in addition to receiving vesicles from the ER?

a- The Golgi apparatus gathers, stores, modifies and packages proteins and fats from the ER into vesicles. These can be sent all over the cell, or exported.

b- It creates a special kind of digestive vesicle called a lysosome.

2. What is a lysosome?

A special vesicle with digestive proteins. It cleans up the cell and digests things the cell captures during endocytosis as well.

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Think pair share

1. What is endocytosis and exocytosis?

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Think pair share

1. [REVIEW QUESTION] Draw an enzyme putting two things together, and draw one taking two things apart.

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Think pair share

1. Draw a cell “eating” some cell food, digesting it, and getting rid of the waste.

Plasmamembrane

Digestive enzymes

Food vesicle is formed.

Lysosome

Cell pinches in here

Digestion2○ lysosome

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Mitochondria are the sites of cellular respiration, which involves the production of ATP from food molecules

Mitochondria

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Think pair share

1. Explain the role of mitochondria.

They turn food into energy packets the cell can use to do work.

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Microfilaments & Microtubules

Microfilaments and Microtubules together make up the cell “skeleton” or cytoskeleton. Cyto= cell. “Cell skeleton”.

Cilia and flagella are made of groups of microfilaments and are external projections that help cells move.

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Cell skeleton or cytoskeleton.

117Artistic view of the cytoskeleton.

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The cytoskeleton is an infrastructure of the cell consisting of a network of microtubules and microfilaments

Function of the cytoskeleton

Maintaining Cell Shape- the Cytoskeleton

– Provide mechanical support to the cell and maintain its shape

– Allow cell to move or change shape.

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Flagella propel the cell in a whiplike motion

Cilia move in a coordinated back-and-forth motion

Cilia and Flagella

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This is an enlarged photograph of a one celled organism using a flagellum to move.

The flagellum moves in a spiral and looks like more than one because this is a time lapse photograph, made with a strobe light.

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Some cilia or flagella extend from nonmoving cells

– The human windpipe is lined with cilia

– These cilia move in a coordinated fashion to move mucus up and out of the windpipe, along with unwanted material (like dust). They “clean” your windpipe.

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Cross section of some cilia, showing the microtubules that run the length of this organelle.

Cilia and flagella are basically a long extension of the cell membrane wrapped around microtubules with some cytosol present.

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Microfilaments are the basic structure in muscle cells.

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Basal body, centriole

Basal Bodies and Centrioles are two more structures made of microtubules. Basal bodies anchor cilia and flagella to the cell membrane. Centrioles are basal bodies that have moved inside the cell and have a role in cell division that we will study later.

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Basal body

Flagellum

Anchoring a flagellum to the cell membrane

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Think pair share

1. List the functions of microfilaments and microtubules.

a- cytoskeleton

b- cilia and flagells

c- basal bodies and centrioles.

2. What does the cytoskeleton actually do?

a-Cell rigidity

b-Ability to move.

3. Function of a basal body?

anchor a flagellum.

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Think pair share

1. What is a centriole?

Basal body that has moved inside cell and has a role in cell division.

2. At right are a bunch of cilia on the surface of lung tissue. What is the function of these cilia?

Move mucous upward and out of lungs- clean the surface of your lung.

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What is going on here?

A flagellum is moving a cell forward.

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Cell membrane

nucleus

mitochondrion

centrioles

Smooth ER

Golgi apparatus

Rough ER

nuceleolus

Either lysosome or vesicle- hard to tell

ribosomes

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PLASTIDS

Plastids are large organelles found in the cells of most plants, but not in the cells of animals.

There are two main categories of plastids: chromoplasts (colored plastids) and leucoplasts (white or colorless plas tids).

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PLASTIDS

Chromoplasts (Chromo = “color”, plast = “container”, colored container).

Chromoplasts give many flowers, ripe fruits, and autumn leaves their characteristic yellow or orange color.

Some chromoplasts give leaves and grass their green color.

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Chloroplasts are the sites of photosynthesis: the conversion of light energy to chemical energy

CHLOROPLASTS

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These are amyloplasts, but they are stained so as to be seen on a slide. They store starch.

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Think pair share

There are two important kinds of plastids. Name them both and give the fxn of each.

1. chloroplast- a chromoplast that is green, specialized to perform photosynthesis.

2. Amyloplast- a leucoplast that stores starch.

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Vacuoles merging in a plant cell. Over time, one vacuole fills the plant cell.

Vacuoles fill with fluid, retain pressure, helping a plant to be rigid.

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Think pair share

1. Cell walls are made primarily of what kind of carbohydrate?

A complex carb called cellulose.

2. Together, the cell wall and ______________ increase a plants rigidity and thus its ability to __________ up

Vacuole , stand.

3. How does the vacuole contribute to this process?

It fills with water, providing turgor.

4. Name another function of a vacuole.

Long term storage of macromolecules.

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AN IDEALIZED ANIMAL CELL

Cytoskeleton

Ribosomes Centriole

Lysosome

Flagellum

Nucleus

Smoothendoplasmicreticulum (ER)

Golgiapparatus

Roughendoplasmicreticulum (ER)

Mitochondrion

Plasmamembrane

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AN IDEALIZED PLANT CELL

Cytoskeleton

Mitochondrion

Nucleus

Rough (ER)Ribosomes

Smooth(ER)

Golgi apparatus

Plasmamembrane

Chloroplast

Cell wall

Centralvacuole

Not in animal cells

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Prokaryotes vs. Eukaryotes

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Prokaryotes versus Eukaryotes

Prokaryotes have no organelles

Example; bacteria

Eukaryotes have organelles

Examples; plants and animals

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Eukaryotic cells

– Are larger than prokaryotic cells– Posses internal structures surrounded by

membranes– Posses a nucleus– May posses flagella or

other external features

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Prokaryotic cells

– Are smaller than eukaryotic cells– Lack internal structures surrounded by

membranes– Lack a nucleus– May posses flagella or

other external features

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Model (above) and electron micrograph (right) of a prokaryotic cell.

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All living cells- common characteristics

Both prokaryotic and eukaryotic cells have these things in common;

– A cell membrane (selectively permeable)

– DNA used to control cell activity and code for proteins.

– Ribosomes- for protein production

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Think pair share

1. Name the major difference between prokaryotic and eukaryotic cells.

Prokaryotes have no nucleus.

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Think pair share

Compare all cells, prokaryotes and eukaryotes

All cells

Membrane

DNA

ribosomes

Prokaryotes

Membrane

DNA

Ribosomes

No nucleus

no organelles

Simpler DNA

Cell walls possible

Cilia/flagella

Eukaryotes

Membrane

DNA

Ribosomes

nucleus

organelles

Complex DNA

Cell walls possible

Cilia/flagella

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Movie clip #3 Play the movie clip- the Cell- 10 min review by clicking on the blue square.

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Movie clip #4 Play the movie clip- 15 min cell review, by clicking on the blue square.

001 Teacher The Cell

Education

Transcript of 001 Teacher The Cell